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//===========================================================================
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//
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// e_sinh.c
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//
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// Part of the standard mathematical function library
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//
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//===========================================================================
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// ####ECOSGPLCOPYRIGHTBEGIN####
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// -------------------------------------------
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// This file is part of eCos, the Embedded Configurable Operating System.
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// Copyright (C) 1998, 1999, 2000, 2001, 2002 Free Software Foundation, Inc.
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//
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// eCos is free software; you can redistribute it and/or modify it under
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// the terms of the GNU General Public License as published by the Free
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// Software Foundation; either version 2 or (at your option) any later
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// version.
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//
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// eCos is distributed in the hope that it will be useful, but WITHOUT
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// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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// for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with eCos; if not, write to the Free Software Foundation, Inc.,
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// 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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//
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// As a special exception, if other files instantiate templates or use
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// macros or inline functions from this file, or you compile this file
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// and link it with other works to produce a work based on this file,
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// this file does not by itself cause the resulting work to be covered by
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// the GNU General Public License. However the source code for this file
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// must still be made available in accordance with section (3) of the GNU
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// General Public License v2.
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//
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// This exception does not invalidate any other reasons why a work based
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// on this file might be covered by the GNU General Public License.
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// -------------------------------------------
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// ####ECOSGPLCOPYRIGHTEND####
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//===========================================================================
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//#####DESCRIPTIONBEGIN####
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//
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// Author(s): jlarmour
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// Contributors: jlarmour
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// Date: 1998-02-13
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// Purpose:
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// Description:
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// Usage:
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//
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//####DESCRIPTIONEND####
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//
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//===========================================================================
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// CONFIGURATION
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#include <pkgconf/libm.h> // Configuration header
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// Include the Math library?
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#ifdef CYGPKG_LIBM
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// Derived from code with the following copyright
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/* @(#)e_sinh.c 1.3 95/01/18 */
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/*
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* ====================================================
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* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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*
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* Developed at SunSoft, a Sun Microsystems, Inc. business.
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* Permission to use, copy, modify, and distribute this
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* software is freely granted, provided that this notice
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* is preserved.
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* ====================================================
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*/
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/* __ieee754_sinh(x)
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* Method :
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* mathematically sinh(x) if defined to be (exp(x)-exp(-x))/2
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* 1. Replace x by |x| (sinh(-x) = -sinh(x)).
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* 2.
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* E + E/(E+1)
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* 0 <= x <= 22 : sinh(x) := --------------, E=expm1(x)
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* 2
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*
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* 22 <= x <= lnovft : sinh(x) := exp(x)/2
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* lnovft <= x <= ln2ovft: sinh(x) := exp(x/2)/2 * exp(x/2)
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* ln2ovft < x : sinh(x) := x*shuge (overflow)
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*
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* Special cases:
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* sinh(x) is |x| if x is +INF, -INF, or NaN.
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* only sinh(0)=0 is exact for finite x.
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*/
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#include "mathincl/fdlibm.h"
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static const double one = 1.0, shuge = 1.0e307;
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double __ieee754_sinh(double x)
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{
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double t,w,h;
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int ix,jx;
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unsigned lx;
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/* High word of |x|. */
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jx = CYG_LIBM_HI(x);
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ix = jx&0x7fffffff;
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/* x is INF or NaN */
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if(ix>=0x7ff00000) return x+x;
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h = 0.5;
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if (jx<0) h = -h;
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/* |x| in [0,22], return sign(x)*0.5*(E+E/(E+1))) */
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if (ix < 0x40360000) { /* |x|<22 */
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if (ix<0x3e300000) /* |x|<2**-28 */
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if(shuge+x>one) return x;/* sinh(tiny) = tiny with inexact */
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t = expm1(fabs(x));
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if(ix<0x3ff00000) return h*(2.0*t-t*t/(t+one));
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return h*(t+t/(t+one));
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}
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/* |x| in [22, log(maxdouble)] return 0.5*exp(|x|) */
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if (ix < 0x40862E42) return h*__ieee754_exp(fabs(x));
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/* |x| in [log(maxdouble), overflowthresold] */
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lx = CYG_LIBM_LO(x);
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if (ix<0x408633CE || ((ix==0x408633ce)&&(lx<=(unsigned)0x8fb9f87d))) {
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w = __ieee754_exp(0.5*fabs(x));
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t = h*w;
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return t*w;
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}
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/* |x| > overflowthresold, sinh(x) overflow */
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return x*shuge;
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}
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#endif // ifdef CYGPKG_LIBM
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// EOF e_sinh.c
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